Your Party leader Yoshimi Watanabe said Monday that his group, which scored great gains in Sunday's Upper House election, has no intention of joining the ruling coalition and urged Prime Minister Naoto Kan to dissolve the Lower House.

"I think the prime minister should gracefully step down — a political gesture that would be in line with the results of the election," Watanabe said. "If he is not going to resign, the prime minister should dissolve the Lower House and call for an election."

The small opposition Your Party became a key holder of the decisive vote in the Upper House by winning 10 seats, bringing its strength in the chamber to 11.